In LTE, if a cell is barred or not, can be decided by two factors.
1. If the parameter cellBarred, which is usually broadcasted in SIB1, is set to barred, then that cell clearly says that it is unable to accept any calls, including the emergency as well as special access class calls. So, source eNB shouldn't take a HO decision in this situation.
2. The parameter acBarringFactor indicates the max value of the UE generated access class, that the eNB can accept. If the value is set to P00 and the same is broadcasted in SIB2, then also the cell is kind of barred. Now, it is completely vendor specific, whether to take HO decision or not, based on this parameter. If source doesn't consider this param while taking HO decision, then, probably source will initiate HO, but, it will fail at target and UE can try to re-establish back to source.